At first view, both the YAMAHA YZ450F and YZ450FX bikes look very similar, but when we look closely at the dimensions of these bikes, we see some differences.
The main difference between YAMAHA YZ450F and YZ450FX is that the YZ450FX features a larger fuel capacity of 2.2 gallons than the YZ450F’s 1.6-gallon capacity. This difference is reflected in the wet weight, with the YZ450FX weighing in at 254 pounds, slightly heavier than the YZ450F’s 240-pound weight.
Specification: YAMAHA YZ450F vs YZ450FX
Engine
| Parameter | YZ450F | YZ450FX |
| Engine Type | 450cc liquid-cooled DOHC 4-stroke; 4 titanium valves | 450cc liquid-cooled DOHC 4-stroke; 4 titanium valves |
| Bore x Stroke | 97.0mm × 60.8mm | 97.0mm × 60.9mm |
| Compression Ratio | 13.0:1 | 13.0:1 |
| Fuel Delivery | Mikuni® fuel injection, 44mm | Mikuni® fuel injection, 44mm |
| Transmission | 5-speed; multiplate wet clutch | 5-speed; multiplate wet clutch |
| Final Drive | Chain | Chain |
Chassis
| Parameter | YZ450F | YZ450FX |
| Suspension / Front | KYB® spring-type fork with speed-sensitive damping; fully adjustable, 12.2-in travel | KYB® spring-type fork with speed-sensitive damping; fully adjustable, 12.2-in travel |
| Suspension / Rear | KYB® single shock; fully adjustable, 12.4-in travel | KYB® single shock; fully adjustable, 12.5-in travel |
| Brakes / Front | Hydraulic disc, 270mm | Hydraulic disc, 270mm |
| Brakes / Rear | Hydraulic disc, 240mm | Hydraulic disc, 240mm |
| Tires / Front | 80/100-21 Dunlop® Geomax MX33F | 80/100-21 Dunlop® Geomax MX33F |
| Tires / Rear | 120/80-19 Dunlop® Geomax MX33 | 120/90-18 Dunlop® Geomax MX33 |
Dimensions
In terms of overall size, the YZ450F stands at 85.8 inches in length, 32.5 inches in width, and 50.2 inches in height, while the YZ450FX is slightly shorter with dimensions of 85.6 inches x 32.5 inches x 50.4 inches.
The seat height on the YZ450F is 38.0 inches, slightly higher than the YZ450FX’s 37.6 inches. Both models share the same wheelbase of 58.3 inches, providing stability and control on various terrains.
The YZ450F has a rake (caster angle) of 26.9 degrees, whereas the YZ450FX boasts a slightly steeper angle at 27.2 degrees. Additionally, the YZ450F has a trail of 4.7 inches, while the YZ450FX has a slightly shorter trail at 4.6 inches.
| Parameter | YZ450F | YZ450FX |
| L x W x H | 85.8 in x 32.5 in x 50.2 in | 85.6 in x 32.5 in x 50.4 in |
| Seat Height | 38.0 in | 37.6 in |
| Wheelbase | 58.3 in | 58.3 in |
| Rake (Caster Angle) | 26.9° | 27.2° |
| Trail | 4.7 in | 4.6 in |
| Maximum Ground Clearance | 13.8 in | 12.6 in |
| Fuel Capacity | 1.6 gal | 2.2 gal |
| Wet Weight | 240 lb | 254 lb |
Summary
The Yamaha YZ450F and YZ450FX are considered a good bike due to their significant weight reduction, enhanced power delivery, improved ergonomics, advanced features like Launch Control and Traction Control, and top-notch suspension, making it a competitive and enjoyable motocross bike.